The invention relates to time delay fuses.
Time delay fuses usually have a fusible element (e.g., a wire) that quickly melts at short circuit conditions (e.g., 30 times the rated current) and another means to break the circuit slowly (e.g., solder that retains a spring-loaded member and melts after the solder and an adjacent heat mass have been raised to a specific temperature, the heat mass providing the delay) at lower overloads (e.g., 2 to 4 times rated current) to permit use with equipment having temporary surges such as motors. Time delay fuses are described in U.S. Pat. Nos. 4,533,895; 3,863,188; 2,321,711; 2,694,124; 4,048,610; 3,144,534; 4,562,420; 2,688,677; 2,613,297; 4,727,347; 2,293,953; 4,321,574; 4,517,544; 2,342,310; 2,386,094; and 2,913,555.